The motions of the retinal image resulting from involuntary eye movements supply temporal changes of illuminance over the receptors. The main purpose of the proposed research program is to explore the question of if and how these modulations in illuminance are used by the human visual system for processing spatial and temporal information. In addition, experiments are outlined in the project which investigate the course of image disappearance which takes place during viewing with a motionless retinal image, with the aim of understanding processes for increment thresholds and brightness discrimination. The psychophysical methods by which spatial and temporal modulation transfer functions are obtained and which for most part utilize the stabilized image method, are supplemented by electrical recordings of the ERG and the EEG. Electrophysiological experiments on the animal visual system, e.g., the cat, are planned to study the interrelation between unit and evoked (peripheral and cortical) and the spontaneous activity under the conditions of a stationary and moving retinal image. In addition, the characteristics of the evoked potential and/or unit activity in terms of the properties of the stimulus will be explored. These experiments will be planned to complement the studies on the human visual systems.